The Golden Age of American Christmas Songs didn't last very long--it appears to have ended in 1963, when Pretty Paper by Roy Orbison, Allan Sherman's version of The Twelve Days of Christmas and Phil Spector's album "A Christmas Gift for You" came out.
Although an occasional Christmas release such as Snoopy's Christmas by the Royal Guardsmen (1966) would come out in subsequent years, the era when one could expect to hear new Christmas songs each year was essentially over.
IMO outside the Carpenters, the only newer songs or versions of Christmas songs worth anything since I was born are “All I Want for Christmas is You” (NOT the terrible dull tuneless Mariah Carey thing), and Bon-E-M’s awesome “Mary’s Boy Child”.